Electricity questions

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Electricity question collection

Review Electricity questions for Physics, with correct answers shown and coverage across current, potential difference and resistance; series and parallel circuits; circuit components.

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Question 1

Which equation gives energy transferred from charge and potential difference?
  1. \(E = QV\)
  2. \(E = IV\)
  3. \(E = \frac{Q}{I}\)
  4. \(E = \frac{V}{Q}\)

Question 2

Charge of \(5\,\mathrm{C}\) passes through a potential difference of \(12\,\mathrm{V}\). How much energy is transferred?
  1. \(60\,\mathrm{J}\)
  2. \(0.42\,\mathrm{J}\)
  3. \(5\,\mathrm{J}\)
  4. \(60\,\mathrm{kJ}\)

Question 3

For fixed Grid power, which combination reduces cable heating?
  1. Higher voltage, lower current
  2. Lower voltage, higher current
  3. Higher voltage, higher current
  4. Lower voltage, lower current

Question 4

Charge flow is given by \(Q = It\). How much charge passes through a wire when \(3\,\mathrm{A}\) flows for \(10\,\mathrm{s}\)?
  1. \(30\,\mathrm{C}\)
  2. \(300\,\mathrm{C}\)
  3. \(13\,\mathrm{C}\)
  4. \(0.3\,\mathrm{C}\)

Question 5

Ohm's law states \(V = IR\). What potential difference does a \(5\,\mathrm{\Omega}\) resistor have if the current is \(2\,\mathrm{A}\)?
  1. \(10\,\mathrm{V}\)
  2. \(7\,\mathrm{V}\)
  3. \(2.5\,\mathrm{V}\)
  4. \(50\,\mathrm{V}\)

Question 6

Which graph best represents an ohmic conductor?
  1. A straight line through the origin
  2. A curve that flattens as \(V\) increases
  3. A parabola opening downward
  4. A horizontal line

Question 7

Which equation links power \(P\), potential difference \(V\), and current \(I\)?
  1. \(P = VI\)
  2. \(P = \frac{V}{I}\)
  3. \(P = V + I\)
  4. \(P = \frac{I}{V}\)

Question 8

Which form of electricity supply is used in UK homes?
  1. Alternating current at \(230\,\mathrm{V}\), \(50\,\mathrm{Hz}\)
  2. Alternating current at \(120\,\mathrm{V}\), \(60\,\mathrm{Hz}\)
  3. Direct current at \(230\,\mathrm{V}\)
  4. Direct current at \(50\,\mathrm{V}\)

Question 9

An appliance rating is \(2\,\mathrm{kW}\). How much energy does it use in \(5\,\mathrm{min}\) (\(300\,\mathrm{s}\))?
  1. \(600\,\mathrm{kJ}\)
  2. \(6\,\mathrm{J}\)
  3. \(60\,\mathrm{kJ}\)
  4. \(6000\,\mathrm{J}\)

Question 10

Charge of \(4\,\mathrm{C}\) flows through a component with \(5\,\mathrm{V}\) across it. How much energy is transferred?
  1. \(20\,\mathrm{J}\)
  2. \(0.8\,\mathrm{J}\)
  3. \(9\,\mathrm{J}\)
  4. \(20\,\mathrm{kJ}\)

Question 11

In parallel circuits, what is the potential difference across each branch?
  1. The same
  2. Different for each branch
  3. Zero
  4. Twice the supply voltage

Question 12

What is the purpose of a plug fuse?
  1. Melt and break an excessive current
  2. Carry fault current safely to earth
  3. Insulate the user from live parts
  4. Reduce the mains potential difference

Question 13

Which equation shows the link between power, current and resistance?
  1. \(P = I^2R\)
  2. \(P = I + R\)
  3. \(P = \frac{I}{R}\)
  4. \(P = IR^2\)

Question 14

Which equation gives energy transferred from power and time?
  1. \(E = Pt\)
  2. \(E = \frac{P}{t}\)
  3. \(E = P + t\)
  4. \(E = P^2 t\)

Question 15

When do light-dependent resistors (LDRs) have lower resistance?
  1. When light intensity increases
  2. When light intensity decreases
  3. When they are cooled
  4. When they are stretched

Question 16

A wire is replaced by one of the same material and thickness but twice the length. What happens to its resistance?
  1. It doubles
  2. It halves
  3. It stays the same
  4. It quadruples

Question 17

What happens if one branch of a parallel circuit breaks?
  1. Current continues in the other branches
  2. Current stops in the other branches
  3. Supply voltage divides between the remaining branches
  4. Current reverses in the remaining branches

Question 18

What happens to a metal heating element's resistance as it warms?
  1. It increases
  2. It decreases
  3. It stays unchanged
  4. It first increases then returns to its starting value

Question 19

What does the earth wire do during a fault?
  1. Carries fault current safely to earth
  2. Carries normal current to the appliance
  3. Returns normal current to the supply
  4. Melts and breaks the excessive current

Question 20

Which statement about bulbs in series is true?
  1. The supply potential difference is shared between the bulbs
  2. Each bulb receives the full supply potential difference
  3. Current is used up by the first bulb
  4. Adding more bulbs decreases the total resistance

Question 21

A \(12\,\mathrm{V}\) battery supplies two resistors of \(4\,\mathrm{\Omega}\) and \(6\,\mathrm{\Omega}\) in series. What current flows?
  1. \(1.2\,\mathrm{A}\)
  2. \(2\,\mathrm{A}\)
  3. \(0.5\,\mathrm{A}\)
  4. \(10\,\mathrm{A}\)

Question 22

Which equation links charge, current and time?
  1. (Q = It)
  2. (Q = I/t)
  3. (Q = V/I)
  4. (Q = IR)

Question 23

A 920 W appliance uses a 230 V supply. What current does it draw?
  1. 4 A
  2. 0.25 A
  3. 690 A
  4. 211600 A

Question 24

What is the main electrical behaviour of a diode?
  1. Conducts readily in one direction
  2. Conducts equally in both directions
  3. Changes resistance with light level
  4. Stores charge like a cell

Question 25

Which component is drawn as a plain rectangle in a circuit diagram?
  1. A resistor
  2. A cell
  3. A lamp
  4. A switch

Question 26

An insulator becomes negatively charged when rubbed. What has it gained?
  1. Electrons
  2. Protons
  3. Neutrons
  4. Atoms

Question 27

Which rod holds a static charge after being rubbed?
  1. A plastic rod
  2. A copper rod
  3. A steel rod
  4. An aluminium rod

Question 28

Which way do electric field lines point around a positive charge?
  1. Away from the charge
  2. Towards the charge
  3. In circles around it
  4. Along its surface only

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Review Electricity questions for Physics, with correct answers shown and coverage across current, potential difference and resistance; series and parallel circuits; circuit components.

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